To allow a further reduction in the structure widths for electronic components, in particular into the sub-micron range, it is desirable to reduce the wavelength of the light used for the microlithography process. For example at wavelengths shorter than 193 nm, lithography with soft X-rays, so-called EUV lithography, offers a conceivable solution.
The wavelengths λ of 11 to 14 nm (e.g., 13.5 nm) can be produced for example by a synchrotron source. However, using a synchrotron source can have the disadvantage that it involves an apparatus of high technical complexity. Alternative EUV light sources are laser-plasma sources in which plasma is produced for example by focusing a laser beam onto a metal plate. Also used as EUV sources are plasma discharge sources where the plasma light source establishes itself in direct proximity to electrodes. In comparison to synchrotron sources, EUV plasma light sources are generally distinguished by significantly lower investment costs. As a drawback on the other hand, EUV plasma light sources are generally characterized by latent instability, and accordingly the source power can fluctuate. Furthermore, because of thermal effects, the source point of the plasma source can migrate.